1. Field of the Invention
This invention relates to a drive system for driving a chopper and feeder device of a harvesting machine, in particular a forage harvester. The chopper and feeder device has a feed apparatus and a chopper apparatus. A drive train is provided for driving the feeder device and the chopper device. The drive train is connected by a coupling device with a drive motor. For driving the feeder device, the drive train has a hydrostatic transmission which includes a pump driven by the drive train and a hydraulic motor connected in a closed circuit to the pump. The hydraulic motor is in a driving connection with the feeder device. A fast stop function is provided, with which the chopper and feeder device is cut off when a foreign object is detected. An electronic control system is in communication with a foreign object detector.
2. Description of Related Art
Forage harvesters take in a crop to be harvested via an attachment. The crop then travels through a feeder device, which is generally formed by a plurality of feed rollers and pre-compression rollers, to a chopper device, generally a chopper drum in which the harvested material is chopped into smaller pieces. After the chopper device, the chopped harvested material is transported into an ejector shaft, in which a treatment device and an ejector blower are optionally located, to transport the chopped harvested material from the forage harvester to a truck.
On conventional forage harvesters, there is a risk that, in addition to the product to be harvested, foreign objects, such as stones or metal parts, can be taken in which can cause significant damage if the foreign objects get into the chopper device with the stream of harvested material. To prevent damage of this type, it is known that foreign objects in the harvested material can be detected with a foreign object detector. If a foreign object is detected, the feeder device can be stopped quickly by an electronic control device, which shuts down the feeder device in a short period of time. To safely prevent a foreign object from getting into the chopper device as it slows to a stop, the chopper device is also shut down quickly. Stopping the chopper device also makes it possible for an operator to safely examine the harvested material to find the foreign object and remove it from the harvested material.
WO 02/09498 A1 describes a forage harvester with a hydraulically driven feeder device, in which, for the fast stopping of the feeder device, a fast stop valve is located in the closed circuit for the drive of the feeder device. To quickly stop the feeder device, the fast stop valve is actuated into a closed position in which a hydraulic fluid line of the closed circuit that forms the return line of the hydraulic motor is shut off and the displacement volume flow supplied to the hydraulic motor by the pump is diverted into a bypass. However, on account of the fast stop valve and the bypass line required, a drive system of this type entails a great deal of added construction effort and expense.
EP 1 721 518 A1 describes a drive system of a forage harvester in which, for the fast stopping of the feeder device when a foreign object is encountered, a switched valve arrangement is located in a hydraulic line of the closed circuit. For quickly stopping the feeder device, the switched valve arrangement closes off the hydraulic line of the closed circuit that forms the return side of the hydraulic motor and carries the delivery flow from the pump past the hydraulic motor into a bypass. To bring the chopper device to a complete stop, an additional brake valve is located on the pump which can shut off a hydraulic line of the closed circuit to brake the chopper device. However, on account of the presence of the switched valve arrangement, the required bypass line, and the additional brake valve, a drive system of this type entails a great deal of added construction effort and expense.
Therefore, it is an object of the invention to provide a drive system of the general type described above with which, when a foreign object is detected in the material being harvested, a fast cutoff of the feeder device and of the chopper device can be achieved with little added construction effort and expense.